The present invention relates to a gyroscope device. More specifically, a gyroscope device is provided that includes multiple disks and is adapted to detect angular velocities while filtering out vibrations and disturbances.
A vibrating gyroscope includes a mass moving in a rotating oscillation around an axis, or oscillating in a linear direction, in a xe2x80x9cprimary motion.xe2x80x9d An angular velocity applied to the gyroscope about an axis perpendicular to the axis of primary motion (rotation or oscillation) causes the gyroscope to rotate (or oscillate) in a secondary motion about a third axis (or in a second direction) perpendicular to the primary motion axis (or direction) and perpendicular to the axis of the applied angular velocity. Gyroscopes are used for detecting angular velocities in applications from airplane navigation systems to dynamic control systems to automobile safety systems, and many others.
Because gyroscopes measure an external angular velocity applied around one axis via the displacement of the gyroscope around a perpendicular secondary motion axis, the gyroscope systems are susceptible to external vibrations and displacements that also cause disturbance motions around the secondary motion axis.
In general, gyroscopes have been constructed with large electromagnetic devices. Recently, however, micro-machined gyroscopes have been developed as part of micro-electro-mechanical systems. Using similar technologies to those used to manufacture semiconductors, microscopic gyroscopes are fabricated on silicon wafers. These technologies may include oxidation of a substrate, application of a photoresist material, selective exposure to light or x-rays through a mask, and etching to build devices in layers on a substrate. An example of such a micro-electro-mechanical gyroscope device is described in PCT Patent Publication No. WO 97/45699. This is a one-layer device employing a single oscillating mass in the gyroscope.
Another example of a micro-machined gyroscope device is described in U.S. Pat. No. 5,635,640 to Geen (the xe2x80x9cGeen patentxe2x80x9d). This is a one-layer device (that is, one layer of components, not counting a layer of substrate). This patent describes a gyroscope with two oscillating masses joined by a spring and driven by a xe2x80x9ccomb drive.xe2x80x9d Such one-layer devices are not isolated or decoupled from the substrate and are therefore susceptible to external vibrations and motions, which may cause noise or failure signals in the gyroscope""s signal by displacing the gyroscope along the secondary motion axis, even when a secondary motion is not induced by an angular velocity applied around the sensitive axis. Furthermore, since the gyroscope is not isolated from the substrate, momentum from the gyroscope or the spring may be transmitted to the substrate and vice versa. A gyroscope adapted to filter out internal and external xe2x80x9cnoisexe2x80x9d forces and momentums and isolated from the substrate overcomes limitations of current gyroscopes.
A gyroscope system is provided comprising at least two disks adapted for motion about a first axis, and a fixed support clamp connected to a substrate. The disks are decoupled from the substrate, and the disks are set in motion about the first axis in a manner that the motion of the first disk is out of phase with the motion of the second disk.